


coup de foudre

by celegant



Category: NCT (Band)
Genre: Alternate Universe - Detectives & Thieves, Heist, M/M, Phantom Thief!Donghyuck, Trope-Typical Violence, detective!mark, flirting on the job, inspired by mark’s 2018 smtown halloween costume
Language: English
Status: In-Progress
Published: 2020-07-23
Updated: 2020-07-23
Packaged: 2021-03-04 19:08:58
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 7,154
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25441426
Author URL: https://archiveofourown.org/users/celegant/pseuds/celegant
Summary: “Mark Lee, was it?”“Yes, sir.”“Are you even aware ofwhoexactly it is that we’re dealing with tonight?” Doyoung asks. “And what’s at stake if we don’t stop him?”(In which there is a heist, a lot of big shiny jewels, and Mark is a homicide detective that finds himself unwittingly playing another one of Donghyuck's dangerous games.)
Relationships: Lee Donghyuck | Haechan/Mark Lee
Comments: 55
Kudos: 205





	coup de foudre

**Author's Note:**

> mark dressed up as conan once and i never got over it. that's it, that's the fic. (also i know jaemin was dressed up as kaito... but hyuck as KID was just calling my name ;;:)
> 
> a special shoutout to julia (as always) and ophelia for beta-ing this chapter, and to vic for listening to me ramble about conan ;;; <33

“Mark Lee, sir. Reporting in from Division One.”

Inspector Kim Doyoung pauses from where he’s seated across the desk, tearing his eyes away from the stacks upon stacks of blueprints and floor plans laid out in front of him. He takes a second to eye Mark’s still figure in the middle of the room—out of place from the hustle and bustle of the other officers in the room around them.

“Division One?” Doyoung raises an arched eyebrow at him. “What’s someone from Homicide doing down at a heist?” His mouth pulls down into a displeased frown, as he looks Mark up and down once more. “You do realize that this is Division Three’s jurisdiction, right? Who sent you?”

“Inspector Lee,” Mark answers simply.

The unimpressed stare that Doyoung sends his way is enough to unnerve him, and Mark fidgets uncomfortably where he stands. Doyoung leans back against his chair, arms raising to cross in front of his chest.

“Inspector Lee?” Doyoung repeats, disdain dripping from his voice at the mention of the name. “Taeyong, of _course_. I should’ve fucking known.”

Mark has no qualms about throwing his commanding officer under the bus for sending him here tonight, not after he’d ignored Mark’s multiple protests about being put on the case. The recollection has him suppressing the urge to sigh because really, he has no business consulting for a potential _jewel heist_ , of all things. Hell, this isn’t even his field of expertise in the first place—there weren’t exactly any dead bodies lying around now, were there?

Plus, he knows Taeyong sent him down just to piss Doyoung off. Mark isn’t exactly keen on working under his boss’ ex-boyfriend, even if it is just for one night. Doyoung’s task force is notorious for vetting anyone that wasn’t handpicked by the man himself, and there’s hell to pay for anyone that got in the way of one of their operations.

He is really, _really_ not looking forward to tonight.

Mark hesitates for a second, sending his boss a silent prayer in his head, before continuing. “Inspector Lee couldn’t make it tonight due to a… prior engagement, so he sent me in his stead,” Mark shrugs and then grins sheepishly. “He says to give you his sincerest apologies.”

Doyoung’s eyes roll upward, and Mark watches as he runs a frustrated hand through his already disheveled hair. He studies Mark for a moment before closing his eyes, brows furrowed as if considering whether Mark’s presence was worth the trouble. A few beats pass before Doyoung lets out a defeated sigh.

“Mark Lee, was it?”

“Yes, sir.”

“Are you even aware of _who_ exactly it is that we’re dealing with tonight?” Doyoung asks. “And what’s at stake if we don’t stop him?”

Of course, Mark knows. There isn’t a single person at HQ that doesn’t know about the heist taking place tonight. It's been all over the news these past few weeks, headline after headline featuring the infamous thief's signature calling card, announcing his plans to steal the royal jewels from right under the police's nose.

Haechan, world-renowned jewel thief, sleight-of-hand magician and international celebrity. Infamous for putting on a show and making a mockery of local authorities when stealing a target, but revered by his beloved audience due to his penchant for returning the stolen items—and most of the time, to their rightful owners.

A modern-day Robin Hood, some of his fans say.

"Yes," Mark confirms. "Inspector Lee debriefed me earlier this morning."

Doyoung reaches over to one of the side drawers on his desk, pulling out a thick manila envelope, filled with what Mark assumes to be all the files related to tonight's case. He gestures for Mark to step forward, before spreading the contents of the envelope out onto the already cluttered desk.

The first thing that catches Mark's eye is the pair of yellow cards, laid out front and center among the mess of paperwork, both signed with a small caricature of a sunflower. Haechan's signature symbol.

Mark reaches out to inspect the cards, but hesitates before picking them up, looking up to Doyoung as if to ask for permission. It must have been the right move, Mark muses, because one of the corners of Doyoung's mouth ticks up in the closest thing to a smile Mark's seen since he'd first entered the room.

"Go ahead," Doyoung says, nodding as he leans back against his chair. Mark murmurs a quick thank you before taking both of the cards in hand for a closer look.

As per Haechan's well-known _modus operandi_ , every heist starts off with a notice, giving the victims and his audience enough time to prepare for his arrival. Delivered to either the precinct or to the jewel's owners directly from the thief himself, the calling cards vary every single time. The cards usually contain a riddle or a poem, sometimes even a haiku—all of which point to the exact date, time, and place for when he's planning on stealing his next target.

It was almost routine at this point. The thief sends out the notice, Doyoung's task force decodes the message, and though the police scramble to increase security at the designated location, Haechan _always_ manages to slip through their grasp—an elusive phantom under the dark veil of the night sky.

Mark frowns as he studies the cards, eyes flitting back and forth between the text. One of the cards was a simple announcement, detailing Haechan's plans to visit the upcoming exhibit on European crown jewels at a private museum north of the city. The second note was more along the lines of what Mark had expected, a short riddle specifying the heist's exact target.

He puts the cards back down, eyebrows furrowed in confusion as he looks back up at Doyoung's expectant gaze.

"Does he usually send more than one notice?" Mark asks. _And one so...obvious, at that. He isn't usually so straightforward._

"Not typically, no," Doyoung answers. "Although, not unprecedented." He pauses, gaze turning scrutinous as he watches Mark frown at his words. "Why?"

Mark just shakes his head in response. There was something about the cards that just felt _off_ , but he didn’t have any proof. At least, not yet. "Just seemed a bit too simple, don't you think? Not really his style."

Doyoung raises an eyebrow at that. "You're familiar with his work then?"

Mark hums. "Something like that," he says, flippant. "I can appreciate a good riddle every now and again, and these ones tend to be unavoidable back in HQ. A lot of the officers try and make it a game to see who can solve it first." Mark stiffens, realizing his mistake. "I mean—before you guys, of course."

"Of course," Doyoung snorts. "Good to know that HQ thinks grand larceny is _fun_."

Mark coughs awkwardly at that, and turns his attention back to the cards. The exhibition is only being held on one day—today—and while it will be open to the public during the museum's regular hours, there was a special viewing tonight for a select few hundred or so individuals.

All that was left for them to decipher was the exact time Haechan was set to appear, and which among the hundreds of jewels was to be the primary target.

"He's not arriving until after the dinner reception then?" Mark says, reading through the first half of the second card.

“Go on,” Doyoung says, regarding Mark with a pleased little smirk.

“ _‘From the lion to the virgin, I will arrive at the cusp’_ ,” Mark recites. “He’s referring to astrology here, right? August 22nd to the 23rd, when it changes from Leo to Virgo. Between 10 and 11 o’clock.”

Doyoung nods, impressed at Mark's deduction. "The dinner lasts until 9:00 pm. And then following that, there's an open viewing for all the guests until two in the morning," he says, handing Mark a document with the event's official agenda. "He never appears without a crowd, so he'll probably wait until people are actually in the exhibition room."

Mark looks up at the clock overhead. 11:28. They just have a little over ten hours before showtime then.

"And the target?" Mark continues. His finger taps on a line of text on the second card. "Whatever it was that was _‘gifted on the eve of Napoleon's second victory’_?"

Mark watches as Doyoung reaches back into the manila envelope, procuring a set of photos that he lays down onto the table one at a time. Mark studies image after image of countless jewelry, all encased behind glass displays within the museum, before settling on the last photo that Doyoung slides in front of him.

“The highlight of the crown jewels exhibit,” Doyoung murmurs, finger tapping on the lavish display of jewelry in the center of the photo. “An emerald parure, from the Archduchess of Austria Marie Louise's very own collection. Napoleon's gift to his second wife, on the eve of their wedding.”

“Parure?” Mark asks.

“Parure," echoes a third voice, chiming in from the entryway, and Mark turns to see Na Jaemin walk into the room. "From the French word _parer,_ which means 'to adorn'. It’s a set of jewels meant to be worn together.”

Jaemin clasps a friendly hand down onto Mark's shoulder when he reaches Doyoung’s desk. “Well, if it isn’t Detective Mark Lee himself,” he says, a charming smile on his face. “Should I be worried that you’re here? Are there any rogue murderers that I should be on the lookout for?”

Mark snorts, before smiling and playfully nudging Jaemin's hand off of him. “Nice to see you too, Jaem. It’s been a while,” he says wryly. “And to answer your question, no—" Mark laughs. "Well, at least I hope not.”

"Jaemin," Doyoung greets dryly, an eyebrow raised at Jaemin's slightly rumpled appearance. "Nice of you to finally join us."

Loosened tie and collar slightly askew, Mark catches a glimpse of what looks like a monster of a hickey starting to bloom right under his collar. Jaemin meets his eye, winking at him as he reaches up to fix his tie, and Mark feels his cheeks heat up at being caught staring.

"Sorry about that, Cap'n," Jaemin grins, absolutely shameless. "Got held up down at Forensics. But I've got what you asked for from Renjun’s team," He reaches into his duffel bag and takes out a folder, passing it over to his commanding officer. "Updated blueprints for the target's room security, sir, fresh out of the oven."

"I never should have assigned you to recon," Doyoung sighs, taking the files. "You were better off on the field. Far, _far_ away from those poor agents down at the office."

"You should be thankful, sir," Jaemin quips. "Our requests are run on double time because of me."

"Yes, yes," Doyoung says dismissively, opting instead to focus on the blueprints in front of him. He pauses then, as if remembering something. "Oh, Jaemin?"

"Yes, boss?"

Doyoung looks up, gaze landing on Mark. "Do you mind giving Detective Lee here a tour of the grounds? He'll be joining us on the floor during the viewing, so he needs to be briefed on security for the jewels."

"Sure thing," Jaemin says, linking arms with Mark. "I've been meaning to catch up with him anyway. I'll take him through the exhibition room and the ballroom for the reception."

Doyoung nods. "Make sure to let Jungwoo know to put Mark on the list for tonight," he says, before turning his attention back down to the files in front of him. "Level 2 clearance."

"Gotcha," Jaemin says, tugging at Mark's arm to get him to move. They're about halfway out the door when he hears Doyoung call out one last time, not bothering to look up from his work.

"Oh, and Mark?"

"Sir?"

"Welcome to the team."

* * *

The conference room where Doyoung and the rest of his team are stationed is located on the first floor of the museum. The building itself is massive—a privately owned estate right on the outskirts of town, surrounded by acres of sprawling gardens. The owners had converted the estate into a museum a few years back, housing an impressive collection of fine art and jewels for the public to peruse.

"The main exhibit's in the east wing of the building," Jaemin says, walking Mark through the foyer. "But I'll show you the ballroom for the reception first, since that's where we'll be spending most of the night. It's just up ahead," he continues, gesturing to the set of grand staircases in front of them. "One floor up from here."

Mark takes a second at the base of the stairs to look around, cataloging the main doors in and out of the building. The museum doesn't open up to the public for another couple hours, but there's already a flurry of activity around them, as staff and security make their rounds in preparation for tonight.

"Is it usually this busy?" Mark asks. “Or is this all because of the heist?”

He sidesteps away from the rush of staff going down the stairs, barely avoiding bumping into somebody behind him, one of Mark's hands reaching out to steady them before they topple down the steps. Mark murmurs a quick apology as they shoulder past him in a hurry, catching up with the rest of the crewmen in front of them.

Jaemin shakes his head, pulling at Mark's arm to tug him along and up the stairs. "It's worse than usual, even when you take the heist into consideration," he says. "It's only because everything is being done on such short notice."

Mark looks over the banister, down over to where security is setting up metal detectors by the main entrance. He doubts that the thief is going to just walk in with the rest of the crowd—not with his kind of track record—but he figures it's better to be safe than sorry.

"What do you mean by short notice?" Mark asks, jogging up the last few steps to catch up to Jaemin ahead of him.

"Haechan usually sends his notices at least a month in advance," Jaemin explains, leading them down the corridor into the main ballroom. His smile turns wry as he glances over at Mark. "And it's only been two weeks since we got the first card, so I’m sure you can imagine how hectic it’s been for the team.”

And then, Jaemin’s voice lowers, almost conspiratorially, as he tries to bite back a smile. “Inspector Kim’s been about two seconds away from an aneurysm the entirety of the past week, so you got off pretty easy."

Mark thinks back to the tense line of Doyoung's shoulders when he'd first stepped foot into that room, and to the scowl he'd caught the tail end of before Doyoung had schooled his expression into something more neutral. As well-revered as he was among the force, Doyoung definitely had _quite_ a reputation when it came to dealing with Haechan in particular, and patience wasn't one of his strong suits whenever the thief was involved.

They pause just by the entrance of the ballroom, not wanting to disturb the staff as they prepare the tables and decorations for the reception. The empty ballroom stands before them, a wide space with high ceilings and a glass dome roof, a singular grand chandelier hanging from the center that illuminates the room in a soft yellow light. The ballroom itself spans multiple floors, curtained opera boxes dotted along the upper floors, overlooking the room.

One odd detail, Mark notices, is that the room is filled with statues, lined up against the pillars surrounding the perimeter of the floor and tastefully scattered between the tables, all in different poses—a little out of place, Mark thinks, compared to the rest of the decor around them.

Jaemin follows Mark's line of sight and laughs a little under his breath. "They look kind of weird, huh?"

"Not...weird, _per se_ ," Mark says. "Just not what I was expecting, I guess?"

"Nah," Jaemin waves a hand dismissively. "They're weird. Stupidly ostentatious too, in my opinion. Although, I reckon they'll look better once they actually put the jewels on them."

"Jewels?"

Jaemin nods. "The owners wanted to highlight some of the royal jewels on the statues themselves. It gives these high-society folks a chance to see them up close and personal during the dinner." He leans in even closer, voice lowering to a whisper so only Mark could hear. "It's all just speculation for now, but I hear a lot of the guests are actually potential buyers for some of the exhibit’s pieces. These jewels are worth a _lot_ of money, even more so now that Haechan is after one of the pieces."

"So this exhibition basically doubles as a pre-auction showcase then," Mark says, humming in consideration. "What's the security detail like for the dinner?"

Jaemin reaches into his messenger bag and takes out a tablet, fingers quickly tapping through as he pulls up the floorplan for the event. “There’ll be officers stationed around the ballroom during the dinner—that’ll be us—and we have control of the CCTVs in every room of the building, so we’ll have full access to surveillance throughout the event.”

Mark watches as his fingers fly across the screen, faster than he can keep up with. He feels his phone vibrate in his pocket, and he takes it out to see a couple of emails from Jaemin himself.

"I've just sent the details for the guest list and the seating arrangements to your phone. Have a look through them when you get a chance," he says, absentmindedly. Jaemin blinks, before looking up at Mark’s curious face. "Oh, and before I forget—"

Mark jumps when he feels fingers pinching at his cheek, wincing when Jaemin pulls harshly at his skin.

" _Ow—_ what?" Mark winces, flinching away at the pain. " _Why_?"

"Just making sure you're actually who you say you are," Jaemin grins, unapologetic. "Haechan is a master of disguise after all, and it wouldn't be very hard for him to sneak in as a recently joined detective."

"Ha ha," Mark grumbles, rubbing at his now sore cheek. "Very funny, Jaem. You've known me for years, was this really necessary?"

Jaemin shrugs, ticking off a box next to Mark's name on his tablet. "Mark Lee or not, I had to check," he says. “There’s a reason why Haechan has managed to pull off half the shit he does. Not only can he _look_ like you, he also has the ability to _sound_ like you.”

“So I’ve heard,” Mark says.

And it’s true. Haechan’s notoriety doesn’t just stop with his job as a masked thief. He’s a magician first and foremost, and he isn’t afraid to use his kit to his advantage—from elaborate disguises and tech designed to trick the audience, all the way to voice mimicry. It’s all part of his appeal at the end of the day, the unbelievable grandeur of it all. The showmanship.

“You really can’t trust anybody these days, sadly,” Jaemin says, shaking his head. "All incoming guests for the reception will have to be screened, although not as uh, _rigorously_ as I just did."

"I damn well hope not," Mark mumbles under his breath. "Staff and security too then?"

"Yep. Plus, the on-shift security's identities will have to be authenticated with rotating passwords throughout the dinner. There's another set of passwords for those stationed in the target's room too."

"I didn't realize you guys were running such a tight ship around here," Mark says, impressed at the task force's level of caution and attention to detail.

"You don't even know the half of it," Jaemin snorts. "Almost three years of losing multi-million dollar items to Haechan would make any man this paranoid, and mix that in with Doyoung's level of neuroticism about everything else? It's a miracle more officers don't quit, really."

He leads them back out to the corridor, heading over to the east wing of the building, and to the room where the main target is being kept for the night.

A few beats of silence pass as they walk, and Mark feels more than sees Jaemin studying him from the corner of his eye.

"Just spit it out, Jaem," Mark says. "You've got a shit poker face."

Jaemin just grins in response, his hands coming up in surrender. "It’s rare for us to be assigned a consulting detective. I'm still just trying to figure out why you're actually here."

"Honestly, I keep asking myself the same thing," Mark shrugs. "But Taeyong apparently got these orders from higher up, so I couldn't really say no."

"Still," Jaemin says. "It's a little too left field, don't you think? That HQ suddenly thinks we need a babysitter." He chances a glance to the side. "No offense."

"None taken," Mark laughs.

"And for someone as harmless as Haechan, too," Jaemin adds on, pouting a little in indignation for the thief.

Mark blinks up at him at the unexpected comment, eyebrows raising in surprise. "If I didn't know any better," he says, voice cautious, "it almost sounds like you're a fan of the guy."

Jaemin shrugs, flashing his badge at the officers by the entrance to the wing to let them through. He doesn't say anything in response to Mark, not until they’re out of earshot of the other officers.

"I mean? Sure, he's a thief and he makes my job a million times harder," Jaemin says. "But I don't think he's actually a bad guy. If anything, his heists are a good break from all the other assholes our team has had to deal with."

"What do you mean?"

They pause by an open set of French doors, leading out into a balcony overlooking the estate's back gardens. Jaemin tips his head over in question, and Mark steps through so they can continue their conversation outside.

"I don't know if you're aware of it, but Haechan only has one rule when it comes to any of his heists," Jaemin continues. "And it’s that no one gets seriously hurt. And I really do mean no one, not even the officers that go up against him."

"Do the other members of the task force feel the same way as you? That he isn’t really that much of a threat?" Mark asks, arms leaning against the balcony railing to take in the view. There's a section of the gardens that consist of a hedge maze, and Mark watches as the museum staff work below them, decorations reaching all the way outside.

Jaemin hums in thought. "Probably," he says after a while, leaning with his back towards the railing. He pulls his tablet back out, and starts working on something that Mark couldn't see. "He's got a strict no gun policy, and yeah, he's annoying and cocky as all hell, but it's all in good fun. Plus, he never keeps any of the stuff he steals anyway."

"Careful there," Mark grins up at him, teasing. "It's starting to sound a little bit like you have a crush."

"He wishes," Jaemin scoffs, a little offended at Mark's accusation. "I have standards, I'll have you know." A beat or two passes in comfortable silence, before Jaemin continues, voice lowering until Mark's straining to hear him. "Although, I guess I _do_ owe him. The benefit of the doubt, at least."

Mark turns his head to look fully at his friend, takes in the fond smile on his face as Jaemin keeps his eyes trained on the tablet in front of him. "Owe him? For what?"

Jaemin finally looks up, pocketing the tablet once more before turning around to mirror Mark's pose against the railing.

"He saved my life once, you know," he says, smile turning a little wistful in recollection. "Took a bullet from a stray sniper that was meant for me, back last year when I was still on the field. Doyoung nearly had a conniption when he saw us both go down, and he still managed to escape anyway."

"Is this why you were re-assigned to reconnaissance?” Mark frowns. “Were you hurt?"

Jaemin shakes his head. "Nothing more than a few bruises," he answers. "Though I couldn't really say the same for him. I didn't know how bad it was until we realized we hadn't heard from him for almost half a year. Honestly, I was even a little relieved the next time we saw one of his calling cards on the boss' desk."

Mark's silent for a moment, taking in the information before he turns his gaze back onto the gardens.

"I guess you're right," he eventually says, a small, knowing smile growing on his face. "He doesn't sound all that bad. I can see why you guys like him."

"Yeah," Jaemin laughs softly under his breath. "He's still a criminal, make no mistake, so we're definitely going to catch him." Then quieter, almost a whisper. "But I guess you can say we're all a little attached."

"Even Doyoung?"

"Even Doyoung."

* * *

Jaemin brings them to the main exhibit room next. A wide space, mostly bare except for where the target is being kept in a glass display in the center of the room. Mark nods at the officers stationed outside its doors.

It’s the only room in the estate that’s been obviously modified, Mark notes. The wooden double doors used throughout the rest of the building were replaced with automatic sliding doors—made with reinforced steel, judging by the thickness of the material as they walked into the room.

"This is it then?" Mark tilts his head at the sight of the emerald and diamond-encrusted jewelry in front of him. "It's not as flashy as I was expecting."

"Mark," Jaemin's voice is flat as he regards the detective next to him. "You're looking at almost 700 carats of diamonds from the 19th century. The diadem alone is almost worth $150 million dollars, not even counting its historical value."

"Sorry," Mark grins, sheepish. “These kinds of things never really interested me. They all kind of look the same, honestly."

A hand reaches out to stop Mark in his tracks just as he takes a step closer to the display.

"Unless you want to set off a million alarms, I'd keep my distance," Jaemin says. "There are weight sensors all around the perimeter of the display, about 2 meters on each side."

Jaemin rummages through his bag before taking out a small pen, tossing it over the rope fencing so it lands a few inches away from the base of the pedestal. Immediately, the automatic doors close and lock behind them, a loud, ear-splitting alarm blaring throughout the room before Jaemin mercifully shuts it off with a few taps on his tablet.

Mark whistles as he uncovers his ears, impressed. "No one gets near this thing without you guys noticing."

Jaemin nods. "Yep, it's sensitive enough to detect something as small as a pen, so not even microtech can make it through."

Mark watches as Jaemin disables the system, reaching under the rope fencing to retrieve the pen before re-activating the alarm. The fence surrounding the display is simple, and Mark assumes that the perimeter is also going to be lined with officers come the promised time. He looks up at the ceiling, where a multitude of small chandeliers hang overhead.

"And above?"

"We've got it covered, don't you worry," Jaemin grins proudly, reaching into his pocket for a small hand-held remote. A press of a button later, and all of the lights are shut off, Mark blinking as he adjusts to the darkness. Jaemin hands him a pair of glasses, Mark wordlessly putting them on without protest.

Red fills his vision as Mark takes in the motion sensor lasers around them, criss-crossing in layers above the pedestal a couple of feet overhead.

"If he tries to come from up top, he'll trip these and the doors will lock," Jaemin explains. "The only people with access to the automatic doors’ system are Doyoung and myself." He raises his hand, palm facing Mark as he wiggles his fingers. “Biometric passwords, baby. We’ve got all the works.”

"Is it like this for all the other exhibits?" Mark asks. He remembers the plans for all of the jewels that will be on display during dinner. "And what about the ballroom?"

Jaemin sighs before answering Mark’s question. "Unfortunately, the owners vetoed us installing the tech anywhere else. They even gave us this room specifically to single out the parure," he replies. “They didn’t want to make too many changes to the building’s infrastructure, apparently.”

Mark removes the glasses, gives them back to Jaemin as the lights turn back on.

"But there's nothing to worry about," Jaemin continues, giving Mark a reassuring smile as he leads them out of the room. "Haechan doesn't go for anything other than his promised target, so the rest of the jewels should be safe where they are."

* * *

Jaemin dismisses him for the rest of the afternoon, leaving Mark to his own devices as he takes his own time patrolling the estate, familiarizing himself with the layout, and ending his stroll with a walk through the gardens. He skims through the files that Jaemin had sent to his phone, going over some of the more notable guests and the schematics for tonight's security detail.

Mark, for the most part, is free to roam around on his own throughout the reception. They won't be needing him until Haechan actually makes an appearance.

He spends the last couple of hours before the event in the task force's conference room, having reconvened with Doyoung to go over the museum's surveillance cameras. He also receives his gear for the night, just before the guests start to arrive for the main event—an earpiece to key into their comms and a small hand-held walkie talkie should Mark encounter the thief at any given time.

Eventually, the evening arrives, and that's their cue to head down to the floor. Mark makes his way down to the far end of the ballroom, away from most of the crowd, keeping tabs on the rest of the officers as they scatter around the room.

He spots Doyoung, flanked by his assistant Jungwoo, off to the side by the entrance, chatting with who Mark assumes to be the owners of the museum. Jaemin meets his eye when Mark's gaze scans the rest of the crowded room, a hand lifting his flute of champagne in greeting before he turns back to his own conversation.

One of the waiters passes by him, offering him his own flute from the tray, and a corner of Mark's mouth quirks up in amusement. One drink wouldn't hurt, and if Jaemin can get away with it, he doesn't see why not.

Plus, he has a gut feeling he’s going to need it tonight.

Drink in hand, he wanders around the statues, admiring some of the pieces adorning the necks and arms on the cold marble figures. Jaemin was right, Mark muses, they did look better dressed up. He lingers on one with a ruby necklace, pendant almost iridescent under the soft lighting, a pair of matching earrings hanging from the statue’s ears.

 _Still gaudy though_ , Mark thinks, taking a short sip of his champagne before moving on to the next display.

He moves to leave the ballroom, eager to take a break from the noise of the crowd, and to take a breather before his shift in the exhibition room. Mark nods to the officers by the door as he makes a quick exit, and his feet bring him to the same balcony he’d visited this afternoon with Jaemin, familiar French doors closed, but unlocked.

Mark chances a look to either side, a habit formed from years on the job, before drawing the curtains back and stepping through the door. He leans against the railing, breathing out a soft sigh of relief at the silence of the night before taking another sip from his drink. The garden below him is lit up, and Mark can spot a few of the guests sneaking out into the gardens with their dates, the hedges filled with fairy lights, illuminating the path to the fountain in the middle.

“It’s quite the romantic view, don’t you think?”

Mark stiffens at the sound of a voice from right behind him, but he wills himself to calm down. He brings the flute back up to his lips for another languid sip, using the action as an excuse to hide his surprise at the other’s presence.

“It is,” he eventually concedes, voice soft. Mark keeps his eyes trained to the garden, making no move to turn around, not even as he feels the other man close the distance between them, soft footsteps almost silent against the concrete floor of the balcony.

“Aren’t you a little early to the party?” Mark asks, with as much feigned nonchalance as he could inject into his voice. “The show doesn’t begin for another hour, at least.”

“I wasn’t really planning on saying hello,” Mark can _hear_ the grin in the other man’s voice, taunting. Always taunting. “But I saw you slip out here and well—” Haechan’s voice dips lower, and Mark suppresses a shiver as he whispers right into Mark’s ear, their bodies almost pressed flush together. “I couldn’t just ignore _you_ , now could I? Not when it’s been so long since you’ve last graced one of my heists with your presence. It’s been what? Six months? Even longer?”

“Haechan—” Mark says, a warning in his voice. He feels his cheeks flush at the proximity, despite himself, and the thief only chuckles once more before stepping away.

Instinctively, Mark goes to turn to face the thief but he freezes, fingers tightening around the stem of his champagne flute as he feels the hard edge of what is presumably a taser dig into his lower back.

“Ah, I wouldn’t turn around if I were you,” Haechan says, a teasing lilt in his tone. It’s the same tone of voice that Mark knows Haechan uses when he knows he’s got his prey right where he wants them. “I’m not quite show-ready just yet, and I wouldn’t want my favorite detective seeing me at anything less than my best.”

“A taser, really?” Mark scoffs, a familiar spike of adrenaline pumping through his veins as he leans back into the taser challengingly. “A little much, don’t you think?”

“Tonight’s a bit of an unusual heist, I must admit,” Haechan says. “I had to come a bit more prepared than usual.” His tone shifts, and Mark can clearly imagine the smirk growing on the other’s face as he continues on. “It’s an _awfully_ convenient coincidence that you’re here, actually. Just the man I needed for the occasion.”

There was something about the way he’d said it that keyed Mark in, the revelation coming to him so suddenly that he couldn’t help the disbelieving bark of laughter that escapes him.

“It was all you, wasn’t it?” Mark accuses. “Me getting assigned here today. That wasn’t Taeyong at the precinct this morning, it was _you_.”

Master of disguises, indeed.

“Bingo,” Haechan sing-songs. His voice changes then, from his own to one that’s much more familiar, one that Mark hears every single day—Taeyong’s voice, coming from right behind him where the thief stands.

Mark sighs and downs the rest of his drink.

“Really, Detective Lee. You lot should be more concerned about the security over at HQ, I just waltzed in there without anyone batting a single eyelash,” Haechan says with Taeyong’s signature drawl. “Now, imagine the scandal if it’d been anyone other than little ol’ me.”

“No one in their right mind would be crazy enough to walk right into the lion’s den,” Mark retorts, leaning his elbows down onto the railing and resting his chin on his palm. His eyes follow yet another couple as they walk into the maze. “No one but you, apparently.”

"Well now, I'm taking that as a compliment," Haechan says, back to using his own voice. He eases the pressure of the taser off of Mark's back, tension bleeding out of Mark's shoulders at the action. "But to go back to the topic at hand, I'm sure you've already figured out why I needed you out here tonight."

Mark hums in consideration. "The fake calling card, right?"

He thinks back to earlier, when he'd studied the two cards—at the seed of doubt that settled in the back of his mind as soon as he'd read that first note.

"Right again," Haechan laughs, a light, twinkling sound. On anyone else, Mark would have probably thought of it as charming, but on the thief, it sounded like a challenge. A provocation, of sorts. "A+ work, I knew hiring you was the right choice."

Mark scoffs. "You're not exactly _paying_ me, now are you—"

"Hush, detective," Haechan interrupts. "Let me finish."

Mark startles as he feels Haechan turn around behind him, leaning his back against Mark's as he continues on, unfazed at the intimacy of their position. He feels the thief relax fully against him, resting his weight on Mark's body almost lazily.

"I didn't send in that first notice," the thief says, all traces of humor gone as his voice dips lower, more serious. "But I did send the second one in hopes of luring them—whoever _did_ send that first one in—out tonight."

"A copycat then?"

It wouldn't be the first time the precinct has had to deal with a Haechan copycat. Doyoung's team had caught a couple of others in the past, but only because Haechan had never bothered to intervene—the copycats' targets were usually small fry, jewels that Haechan would never have gone for himself.

The mediocre thieves were no match for Doyoung's task force in the end, not after years of dealing with the real thing.

"Maybe," Haechan murmurs. "It's odd though, that they'd go for something as high-profile as this. Surely, they'd have known that Doyoung would pull out all the stops?"

"Ballsy copycats, then," Mark snorts. "So that's why you decided to step in? You think these guys are different this time around?"

"Yeah," Haechan says. "Call it a gut feeling but something tells me these guys aren't as dumb as the last ones. Smart enough to get me to come out, at least. And potentially more dangerous," he trails off during that last bit, before Mark feels him shake his head. "Nevertheless, they certainly won't be playing by my rules, and I can't guarantee everyone's safety if they decide to join in on the fun."

"Are they after the jewels?" Mark frowns, eyes glancing to the side. "Or are they after _you_?"

"I don't know," Haechan replies, quietly, uncharacteristically somber. A few beats of silence pass between them before the thief lets out a breathless little laugh, tipping his head back against Mark's playfully in an attempt to lighten the mood. "Given that though, I've got a favor to ask of you."

Mark raises an eyebrow, even though he knew the other couldn't see him.

"You do realize you're talking to an officer of the law here, right? That's probably violating like, a million different rules?" Mark says, a small smile on his face, at the absurdity of it all. "A homicide detective, liaising with a known criminal. They'd fire me in a heartbeat."

"Not if you don't get caught, they won't," Haechan says, tone slightly condescending, as if not getting caught was the easiest thing in the world.

Although for him, Mark muses, it probably is.

"But don't worry," Haechan continues. "I don't need you to do anything illegal. You can leave all the fun stuff to me."

"What is it then?"

A beat or two passes, and Mark doesn't get a reply. Haechan straightens up, a weight off of Mark's back as he moves to leave. Mark turns around, determined to catch a glimpse of the thief's face—

But Haechan snaps his fingers, the lights in the garden below shutting off all at once, leaving their balcony enshrouded in darkness.

Mark blinks as his eyes adjust to the dark, barely making out Haechan's silhouette in front of him. Slivers of moonlight shine down on the both of them, peeking through the overcast clouds overhead. Most of the thief's face is hidden in the shadows, but Mark can see Haechan's grin, sharp and dangerous in its own right, directed straight at him.

"The favor, my dear detective," Haechan whispers, "is for you to watch over yourself, and the rest of my beloved officers, during the heist tonight."

Mark's brows furrow at the request. It wasn't what he was expected at all, least of all from the thief himself.

One of Haechan's hands reaches up to tug the brim of his hat lower, obscuring more of his face from Mark's view. "You're the only one here that I'm willing to trust," he clarifies. "And I don't appreciate seeing the people I like get hurt, not if I can help it."

Mark's earpiece springs to life as multiple officers report in the power outage outside.

"So? What'll it be, Detective Lee?"

Mark studies the figure in front of him, and against every learned instinct within him, he nods.

"You have my word," he says, voice steady. “I'll look after the team.”

Haechan's grin widens, and Mark feels a little like he's just made a deal with the devil.

"Exactly the words I wanted to hear," the thief says. "Although with that being said, I'll be taking that as my cue to leave."

"Wait—"

"See you down at the show floor, detective. And as always," Haechan says, voice low as he raises his other hand in front of him, fingers poised to snap once more.

" _Try and catch me if you can._ "

A snap, and the lights come flooding back on, Mark momentarily distracted by the sudden brightness, and the sounds coming from the crowd below. By the time he looks back up, the thief is gone, not a single trace of his presence left behind.

"—tive Lee. Detective Lee!"

Mark brings a hand up to his earpiece, the other bringing the small walkie-talkie closer to his face.

"Detective Lee, reporting in, sir. What’s wrong?"

"Come down to the surveillance room,” Doyoung's voice crackles over the comms. “There's been a breach."

"I'll be right there."

Mark's hand drops down to hang limply beside him, turning around one last time to look at the gardens below. He freezes though, at the sight of a small, solitary blue rose, left behind in his empty champagne flute.

Mark picks it up gingerly, admiring the petals for a moment before he pockets it within the safety of his inner jacket, patting it once before heading back inside.

_It's showtime._

**Notes for the Chapter:**

> [curiouscat](https://curiouscat.me/dhyuckiees) | [twitter](https://twitter.com/dhyuckIees)
> 
> i can't believe im actually writing a fic based off of detective conan... what have i become ksdjs please let me know what you think!! this is so different from any of the other stuff i've written ;;; but it's been fun to write, so I'll hopefully have the second chapter up soon!! <3


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